Design of AC-coupled low gain avalanche diodes (AC-LGADs): a 2D TCAD simulation study

Abstract

AC-Coupled Low Gain Avalanche Diodes (AC-LGADs) are a new type of silicon sensors which conceived for experiments at future colliders. As an evolution of the standard Low Gain Avalanche Diodes (LGADs), AC-LGADs have similar fast timing performance. The innovation is that AC-LGADs are available to provide fine temporal and spatial resolution simultaneously, thanks to two key features: AC-coupled readout through the dielectric layer and a continuous resistive n+ implant. The Institute of High Energy Physics (IHEP) High-Granularity Timing Detector group is developing its first version of AC-LGAD sensors. This paper present the impact of following parameters on AC-LGAD sensor performance: n+ dose, dielectric material and thickness, pad/pitch ratio and the distance between pad and cathode. All data are obtained from 2D Technology Computer-Aided Design (TCAD) simulations. The simulations will benefit future design and optimization.